Lighting standard for station lights

Table lamp is a common lighting product in life, which can be used for reading and writing homework lighting or room transition lighting. Another important indicator of the lighting effect of desk lamp is illuminance and illuminance uniformity. Let's look at the illumination standard of Taiwan Province lamp.

The lighting standard of the station lamp is 1 1. According to the division of indoor space function, the daylighting standard of residential buildings is also different. Generally speaking, the lighting in the living room and dining room will be higher, and the lighting in the rest places such as bedrooms will be lower. For example, if the living room is only used for general activities, its daylighting standard is 100lx, and if the desk arranged in the living room is used for writing and reading, its mixed daylighting standard is 300lx. The lighting standard of the restaurant is 150lx. The lighting standard of the general activity place in the bedroom is 75lx, like reading at the bedside, and its mixed lighting standard is 150lx and so on.

2. The illumination in offices and other places is usually relatively high. Generally speaking, the illumination standard of ordinary offices, conference rooms, service halls and other places is 300lx. If it is a video conference room, the illumination of the design room will be higher. The lighting standards are 750lx and 500lx respectively. The lighting standard of general supermarket business hall is 300lx. If it is a high-end business hall, its lighting standard is 500lx. The lighting standard value of high-grade indoor commercial street is 300lx.

In places like cinemas, theatres and concert halls, the lighting changes according to different functions. For example, the lighting standard of cinema auditorium is 100lx, the lighting standard of cinema audience lounge is 150lx, the lighting standard of rehearsal hall is 300lx, and the mixed lighting standard of dressing table is 500lx. If it is a general reading room, the lighting standard is 300lx, and the lighting standard of the reading room for the elderly is 500lx.

Main evaluation indexes of desk lamp

Table lamps have a wide range of applications, including not only the most common reading and writing lamps, but also the lamps that provide vertical lighting at the bedside and transitional lighting in hotel rooms. The application of the latter two types of products does not require high visual work, so the product requirements are simple. For reading and writing desk lamps, the national standard puts forward a complete evaluation index and test method, which mainly evaluates the products from the perspectives of product performance consistency, product safety and harm to human body. GB/T 9473—20 17 "Performance Requirements for Reading and Writing Desk Lamps" is applicable to desk lamps used for reading and writing lighting and claiming "eye protection" in families, classrooms and similar places [1]. At the same time, China Quality Certification Center (CQC) also launched the certification business of reading and writing desk lamps, and issued CQC16-465316-2018 "Performance Certification Rules for Reading and Writing Desk Lamps". According to the above standards and requirements, the indicators for evaluating table lamps mainly include: ① light and color characteristics-illuminance and illuminance uniformity, shading, chromaticity tolerance, color rendering index and flicker; (2) safety-the harm of retinal blue light, electromagnetic radiation, noise and the safety of portable lamps; ③ Electrical characteristics and others-input power, power factor, appearance and signs.

Product quality inspection should first ensure the safety of products, followed by functional evaluation, that is, whether it can cooperate with different uses and provide a comfortable and efficient visual working environment. Among the indicators related to the light and color characteristics of products, chromaticity tolerance is an evaluation of the light quality and consistency of products, and color rendering index is an evaluation of the degree of color reduction of light on objects. In addition, because the light-emitting surface of general products is 40 cm, which is generally consistent with the detection position required by the standard, few products will fail to shade. The flicker characteristics of desk lamps due to the improvement of product manufacturing technology, the qualified rate is rising. However, illuminance and illuminance uniformity, as the main indexes to evaluate the lighting performance of the platform, are often ignored.

Requirements and test methods of illuminance and illuminance uniformity in station lighting standard 2

The lighting task of the desk lamp for visual work is to provide a comfortable and reasonable lighting environment and help people to complete visual tasks such as reading and writing efficiently and comfortably. It is found that among various environmental factors, people's ability to see objects clearly (visibility) is mainly determined by three factors: object size (viewing angle), illumination and contrast (brightness ratio of objects to background). Therefore, once the visual task is determined, the size and equivalent contrast of the object are determined unchanged, and illumination becomes the main factor affecting the visual work efficiency. Referring to the importance of each visual task, combined with the size and equivalent contrast characteristics of related visual work objects, the required illuminance standard value can be determined. Illumination not only affects visual efficiency, but also affects visual fatigue [2]. Therefore, the illumination level has a very important influence on improving people's visual work efficiency, comfort and eye fatigue. In view of the font size of books, reading and writing are very important and subtle visual tasks in people's lives. According to GB 50034-20 13, the illumination limit required in different places related to reading and writing tasks is 300~500 lx.

Besides the illumination level, the uniformity of illumination distribution also has a direct impact on visual fatigue. The research shows that under the same illumination, good illumination uniformity is helpful to reduce visual fatigue. When the contrast between light and dark reaches 3∶ 1, the human eye will obviously feel the change of light and dark [3]. This is mainly because when reading and writing, if the illuminance in the line of sight is uneven, the human eye needs to adjust the pupil size frequently to adapt to different light and dark environments, so it is easy to cause visual fatigue [4].

Considering the above factors comprehensively, illuminance and illuminance uniformity are two basic and important detection indexes when evaluating the lighting environment quality provided by desk lamps. According to GB/T 9473-2017 "Performance of Reading and Writing Desk Lamps", the two requirements are combined into one index, and the test results are divided into three grades: AA, AA and unsatisfactory AA, and the requirements are reduced in turn. See table 1 for standard requirements and figure 1 for test layout method. During the measurement, the vertical projection point of the geometric center of the light outlet of the lamp is taken as the center, and two detection areas are defined in the projection range near the eyes according to the distance from the center point. The test items defined in the standard actually include two indicators: minimum illuminance and illuminance uniformity, that is, each area needs to meet two conditions at the same time before the test of the item is qualified.

Lighting standard for station lights. Difference between illuminance and light intensity

There is no concept of "light intensity" in photometry. Commonly used optical quantity concepts include luminous intensity, illuminance, light emergent degree and brightness. "Light intensity" is just a popular expression, and it is hard to say which photometric concept it corresponds to. The concepts mentioned above all have strict physical definitions:

Luminous intensity: luminous flux emitted by a light source in a unit solid angle, in Candeira, that is, per sphericity 1 lumen.

Illuminance: luminous flux per unit area of illuminated surface, in lux, that is, per square meter 1 lumen.

Light emittance: luminous flux per unit area of light source, the unit is the same as illuminance.

Brightness: luminous intensity per unit area along the normal direction, or luminous flux per unit area within a unit solid angle along its normal direction, in nits, that is, per sphericity per square meter 1 lumen.

Because the luminous intensity and brightness are related to the direction, it is easy to deduce that the luminous intensity of all light sources with the same brightness in the direction is the cosine function of the direction, and the luminous intensity in the normal direction is the largest, which is called cosine radiator or Lambert light source. The brightness of light sources with equal luminous intensity in all directions is not equal.

Luminous intensity, emittance and brightness all represent the luminous characteristics of a light source. Considering the square of the distance from the sun upstairs to the earth is to use the sun as a point light source and calculate the luminous intensity of the sun by using the illumination of the ground. Take the side of the sun facing the earth as a surface light source, and divide it by this area, which is the brightness of the sun in the direction connected with the earth. Of course, this is lower than the luminous intensity or brightness of direct sunlight, because sunlight will be attenuated after passing through the atmosphere.

These optical quantities all use luminous flux, which is an optical quantity corresponding to radiant energy flux, because light is an electromagnetic radiation. The radiation energy flux of electromagnetic wave 1W with different wavelengths is different. When converting it into light flux, the spectral sensitivity curve of human eyes should be considered, that is, the light that human eyes feel for the same radiation energy flux with different wavelengths is different, such as infrared light, microwave and ultraviolet light, which are invisible to human eyes, while visible light with wavelength of 400nm to 760nm is visible to human eyes.

Physical optics also mentions "light intensity", that is, Maxwell equations are used to solve the electric vector of light. The square of electric field intensity is the light intensity in physical optics, which is mainly used to calculate the pattern obtained by interference and diffraction effects.

Light intensity is a vague concept in various related disciplines of optics, and different branches have different opinions, some of which are equivalent to luminous intensity, some are equivalent to light illuminance, and some are equivalent to light brightness. These concepts in photometry have strict physical significance.

Because the illumination of the ground is the illumination produced by the brightness of the sky and the whole environment on the earth, including the brightness of all parts of the sky and the brightness of the light reflected and scattered by other reflectors on the ground, it is difficult to calculate with a direct formula. However, you can realize your idea with the help of imaging optical system. You can use a photographic objective or simply use a magnifying glass. You can image some light sources, such as the sky or something else, on the image surface, and put a photometer on the image surface to measure the illuminance e, then e = 1/4πKL(d/f')2. The 2 in the formula is square and should be superscript, so I can't type it here. K is the transmittance of the optical system, L is the required brightness, D is the aperture of your imaging system, and F' is the focal length of the imaging system. If it is a photographic objective, D/f' is the reciprocal of the aperture number. This formula can be used to convert illuminance into brightness. This formula is used to calculate the illumination or known illumination of the image plane when imaging at infinity, and then calculate the brightness of the object at infinity.